Animal litter

ABSTRACT

An animal litter with increased moisture retention and accelerated absorbency, a method of manufacture and method of use for indoor urine and feces disposal. An animal litter with a greater surface area and higher moisture retention intended for animals as small as mice, gerbils and hamsters, as well as larger domestic animals. The animal litter is a paper and wood composition treated with a surfactant, which increases moisture retention four to five times its weight.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 12/561,393filed Sep. 17, 2009, which is a continuation-in-part of U.S. applicationSer. No. 12/015,583 filed Jan. 17, 2008 which, in turn, claims thebenefit of U.S. provisional application Ser. No. 60/885,449 filed Jan.18, 2007, all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an animal litter with increased moistureretention and accelerated absorbency, a method of manufacture and methodof use for indoor urine and feces disposal.

2. Background Art

Animal litter is typically used for indoor urine and feces disposal tosimulate the natural instincts of animals to excrete in soft soil foreasy burial. The litter is generally composed of clay, recycled paper,or silicate-based granular material. A deodorant or fragrance may beadded to mask the odor of the urine and feces.

Small animals kept in cages such as mice, hamsters and gerbils requirefrequent changes of the litter to keep cages clean and sanitary.Laboratory animals also require a non-toxic litter to reduce the effectof the environment on animal testing. Many animal litters are notbiodegradable and they are difficult to dispose of by flushing thelitter down the toilet. Alternatively, the amount of litter disposed ofin landfills leads to an enormous amount of waste that is notbiodegradable.

There is a need to produce an animal litter material which is morehighly absorbent. Additives have been used to improve moisture retentionand increase the time between changes of the animal litter. However,these additives frequently increase the cost of the litter material, andare not always as effective as desired for their intended purpose. Thereis also a need to have an animal litter that is biodegradable, does notclog toilets and reduces the amount of non-degradable waste inlandfills.

SUMMARY OF THE INVENTION

The present invention provides a composition for an animal litter with agreater surface area, composed of paper and wood. This composition istreated with a surfactant which provides a composition with the abilityto retain moisture in amounts of up to approximately four to five timesits weight. The composition may also contain additional ingredients forodor and moisture control, dyes, pigments, and the like. It is furtheran object of the invention to provide a method of manufacturing theanimal litter, and processes for use as litter in collecting urineand/or feces of animals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a process flowchart for forming a clumping littercomposition according to one or more embodiments of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In one embodiment of an animal litter, the product comprisesfinely-divided paper, and/or finely-divided wood, and a surfactant. Thefinely-divided paper and wood are liquid absorbent in and of themselves.The addition of a surfactant increases the liquid retention propertiesof the paper and wood particles, and also speeds liquid absorption. Itcan increase the absorption approximately four to five times the weightof the animal litter.

In one variation, the animal litter includes: approximately 60% to 85%by weight of finely-divided paper, more preferably 70% to 85%;approximately 15% to 40% by weight of finely-divided wood, morepreferably 15% to 30%; approximately 0.1% to 1.0% of a deodorizer,preferably 0.5% by weight; and approximately 0.1% to 0.5% by weight of asurfactant, the percentages totaling 100% by weight. A highly preferredembodiment utilizes approximately 80%+/−2% by weight of finely-dividedpaper, approximately 20%+/−2% by weight of finely-divided wood,approximately 0.5% by weight of the deodorizer, sodium bicarbonate, andapproximately 0.2% by weight of the surfactant, polyoxyalkylene glycol,to prepare an animal litter with high moisture retention properties. Inanother variation, the pH of the resulting animal litter should beadjusted to be slightly acidic between (pH 3.5 and 5.5) to control theamount of ammonia gas and hence odor released from urine absorbed by theanimal litter. Choice of weak acids to adjust the pH must be balancedwith compatibility with the surfactant and deodorant utilized in theanimal litter. In the inventive compositions, each integral percentageof each ingredient between the broadest end points of that ingredient isconsidered as fully disclosed herein, and part of the disclosedinvention.

The method of manufacturing described produces a softer animal litterthan those containing coarser materials such as clay. Research has shownthat smaller animals prefer finely granulated litters, presumablybecause they have a softer feel. Larger animals such as rats, rabbitsand guinea pigs prefer a slightly larger granulated litter. Softeranimal litters are also preferred by the laboratory animal managementindustry for use with automated bedding dispensers.

Additionally, an animal litter composition with an increased rate ofabsorbency is a preferred factor in reducing the number of litterchanges and reduces the amount of animal waste which passes to thebottom of the animal housing unit.

The method of manufacturing is similar to U.S. Pat. No. 6,158,167 for“Mulch Flakes” herein expressly incorporated by reference which are apaper and wood-based material treated with a surfactant and mixed with aliquid to produce a slurry capable of use in hydro-mulching tanks to besprayed on the ground.

An appropriate concentration of a deodorizer and additional organic orsynthetic absorbent materials may be included to control odors andreduce moisture. Such fragrances and deodorants are well known to thoseskilled in the art. Examples may be found in U.S. Pat. Nos. 5,100,600;5,888,345; 6,635,344; and 7,163,737, all herein incorporated byreference. In addition, dyes and pigments may be added to produce anaesthetically pleasing color, or a color which may influence an animal'sdecision to use the litter. Neutralizing substances such as calciumcarbonate or magnesium carbonate may also be added.

The surfactants used may be any which promote the wetting of the paperand wood fibers. These surfactants may be anionic, cationic,zwitterionic, or non-ionic. Examples of relatively inexpensive ionicsurfactants are the alkylbenzene sulfonates and naphthalene sulfonates.Fatty acid salts may also be useful for this purpose. Preferred for useas surfactants, however, are non-ionic polyether surfactants such aspolyoxyethylated, polyoxypropylated, and both polyoxyethylated andpolyoxypropylated compounds having active hydrogen atoms. Other alkyleneoxides can in principle be used to prepare the preferred surfactants,but are in general more expensive than those prepared from ethyleneoxide and/or propylene oxide.

The oxyalkylation may be block, random (heteric), block random, or anydistribution which provides the necessary wetting properties. Unless ofvery low molecular weight (<500 Da), surfactants prepared from higheralkylene oxides such as propylene oxide and butylene oxide have littleif any wetting action. Reference may be had to NONIONIC SURFACTANTS,Martin Schick, ed., Marcel Dekker (1987) for suitable wetting action.Examples include: polyoxyethylated aliphatic alcohols, phenol,alkylphenols, glycols, glycerine, etc. Nonylphenol ethoxylates and blockpolyoxyalkylene polyethers having at least one hydrophobic moiety andone hydrophilic moiety are preferred. In principle, surfactants such aspolyoxyalkylene polysiloxane copolymers are also useful, but these tendto be more expensive. Surfactants containing glycosidyl radicals andpolyglycosidyl radicals are also suitable.

Tests for suitable surfactants and the amount required are readily madeby preparing a surfactant-free litter product, adding the surfactantbeing tested, neat, as a suspension or dispersion, or dissolved insuitable solvent (preferably water, lower alcohols, acetones, ormixtures thereof), the surfactant-containing litter is dried, and testedas such or after being compressed to a felt-like product. A known weightof water is added and the time to its complete absorption measured.Surfactants with different wetting abilities can easily be compared bythis method.

The animal litter of the preferred embodiment for small animals may beproduced as follows: Recycled newspapers are shredded and processedthrough a hammer mill or similar equipment. The resulting paper piecesare next introduced into a finish hammer mill or similar equipment.Additionally, an appropriate amount of sawdust is added to the finishhammer mill. The approximate sizes of the components to be added to thefinish hammer mill may include: Paper approximately ¼ to 1½ inches inlength, and sawdust passed through a 20-mesh screen. A liquidsurfactant, for example, a polyoxyalkylene glycol, and a fragrance ordeodorant may be included in the correct proportion to the mixture ofsolids. The resultant mixture is granulated to produce the animal litterproduct. The finished product is processed to select the desired finelygranulated litter. The various components are predominantly present asan intimate mixture in the granules thus formed. A simple mixture offinely divided paper and wood fiber is not suitable for use as a litterproduct.

Domestic animals, particularly cats, are typically trained to urinateand defecate in a specially provided litter box. Absorbent materials areapplied to the litter box to collect the urine and feces (i.e., dross).A major problem with the absorbent materials is that after a relativelyshort period of time, the soiled absorbent materials emit objectionableodors due to the presence of the urine and fecal matter.

In order to reduce or eliminate these objectionable odors, fecal mattermust be periodically removed from the absorbent materials. However,physical removal of the fecal matters does not reduce or eliminate odorscaused by the urine absorbed into the absorbent. The homeowner must thenwash the litter box and refill it with fresh absorbent material. Theseactivities are, however, unpleasant, time-consuming and expensive.

Litters have subsequently been developed that allow the homeowner toscoop portions of litter that have absorbed the urine, thus removing oneof the primary sources of odor. Various clays have been used as a basematerial for absorbent animal litters for some time. These materialsbecome tacky when wetted, thereby forming a “clump” that is easilyremoved when cleaning a litter box. Many animals, cats in particular,will often refuse to use a litter box that is not kept scrupulouslyclean. Clumping animal litters facilitate ease of cleaning sinceotherwise the litter box must be periodically dumped and refilled tomaintain appropriate cleanliness. However, conventional clumping littershave been met with limited use as they tend to break, disintegrate,create dust, or crumble, and therefore result in consumerdissatisfaction.

In another embodiment of the animal litter, the litter includes (a) amilled wood material, (b) a milled paper material, and (c) a bentonitewherein components (a), (b) and (c) are intermixed together to form anadmixture and the admixture is pelletized, granulated, and/or flaked toprovide granules, pellets and/or flakes.

In yet another embodiment of the animal litter, the litter includes amilled paper material intermixed with a bentonite and configured asgranules, flakes, or both. In this embodiment, the litter does notcontain any wood material to reduce bulk density. In one variation, thelitter can further include guar gum to provide additional clumpingeffect and at the meantime, increase the organic content of theresultant litter. In certain instances, the milled paper materialincludes shredded newspaper, or particularly shredded recycled newspaperto further reduce cost.

The milled paper material, or together with the milled wood material,should be provided in an amount of 40 to 75 percent, 45 to 70 percent,or particularly 50 to 60 percent by weight, of the total weight of theanimal litter.

In certain instances, the animal litter, when configured as granules, isprovided with a density of from 16 to 24 lbs/ft³, of from 18 to 22lbs/ft³, or particularly 20 lbs/ft³. In certain other instances, theanimal litter is provided as granules such that at least 90 percent byweight of the animal litter flakes have a size of from 0.5 to 6 mm, or 1to 5 mm, or particularly 2 to 4 mm in the longest dimension. When thelitter granules are further divided or granulated to form flakes, theresultant litter is provided with reduced bulk density and increasedvolume-to-weight ratio.

In certain instances, the animal litter, when configured as flakes, isprovided with a density of from 14.5 to 17.5 pounds per cubic feet(lbs/ft³), of from 15.0 to 17.0 lbs/ft³ lbs/ft³, or 15.5 to 16.5lbs/ft³. In certain other instances, the animal litter is provided asflakes such that at least 90 percent by weight of the animal litterflakes have a size of from 4.2 to 9.5 millimeters (mm) in the longestdimension. In certain other instance, the animal litter is provided asflakes such that at least 90 percent by weight of the animal litterflakes have a thickness of from 3.2 to 6.4 mm.

The milled wood material, according to one or more embodiments of thepresent invention, can be sawdust, wood shavings, or de-fibered woodmaterial. The milled wood material can be provided with a length rangingfrom 0.5 mm in the case of sawdust to 50 mm in the case for fibrousfibers and any length in between is also suitable dependent upon theparticular application at hand. When used as the milled wood material,the fibrous fibers can be provided with a fiber diameter of from 100 to1000 microns, 200 to 800 microns, or particularly 500 microns.

The milled paper material, according to one or more embodiments of thepresent invention, can be provided with a size in length ranging from0.5 mm in the case of highly processed, finely divided short fibers to20 mm in the case of shredded paper pieces. Any length in between isalso suitable dependent upon the particular application at hand.

Several benefits can be realized with the clumping litter compositiondescribed herein. By intermixing the bentonite with the milled wood andpaper materials, the bentonite is intimately compounded into andimpregnated within the fibers of the wood and paper materials, such thatthe clumping effect of the bentonite can be realized throughout thevolume of each granule or flake of the final litter product. Thus, thebentonite penetrates into the core of each litter granule or flake, andas a result, accidental breakage or disintegration of a wetted clump canbe effectively reduced.

Unlike related art materials that comprise a substrate and a coatingthat provides clumping action, the clumping litter composition accordingto one or more embodiments of the present invention utilizes an intimatemix of milled wood and paper materials and bentonite to form a uniformlymixed litter product. No separate coating is used thereby reducing themanufacturing cost. Further, in certain instances, the littercomposition includes more than 50% by weight recycled paper and woodfibers, further reducing the product cost given the very low cost ofthese fibers from lumber mills and the like. In certain other instances,the litter composition is configured as granulates and/or flakes enhancesurface area and hence moisture absorption.

Bentonite has been conventionally used alone as the base absorbent of alitter composition. This conventional use comes with issues asbentonite, when used alone, tends to aggressively stick to the sides andbottom of a litter box when wetted. This tendency makes removal of theclumped litter more difficult, sometimes partially defeating the purposeof the clumping action afforded by the bentonite. Litter stuck to thesides and bottom of the litter box also requires more frequentreplacement of the litter box itself. This problem has been effectivelydealt with according to one or more embodiments of the presentinvention, wherein the litter composition results in softer clumps withwetness penetrating throughout each of the clumps that stick togethersufficient for relatively easy removal.

The litter composition containing the paper and wood fibers intermixedwith bentonite, according to one or more embodiments of the presentinvention, is provided with a desirable volume/weight ratio due to thegeneral lightweight of the paper and wood fibers and is concurrentlyprovided with a desirable dumping benefit as a result of intimateinteractions between the fiber materials and the bentonite.

As the bentonite is intimately mixed with the other components of theanimal litter composition, the clumping effect of the bentonite ismaximized per a given amount. Therefore, relatively less amount ofbentonite can be used, and hence more cost benefits can be realized asbentonite is in general quite expensive.

In another embodiment, the clumping litter composition further includesat least one colorant agent. The colorant agent includes dyes,including, but not limited to, direct dyes, vat dyes, sulfur dyes, aciddyes, mordant acid dyes, premetalized acid dyes, basic dyes, disperseddyes, reactive dyes, azo dyes, phthalocyanine dyes, anthraquinone dye,quinoline dyes, monoazo, disazo and polyazo dyes. The colorant agent canalso include one or more pigments which selectively reflect and absorbcertain wavelengths of light. The reflected light spectrum creates theappearance of a color. Sunlight creates a more uniform spectrum thanartificial light. There are many pigment groups which may be combined toform specific colors. Some pigment groups are more compatible thanothers which increases or decreases the intensity of the color. Thepigments can be selected from the pigment groups consisting of: arsenicpigments, carbon pigments, cadmium pigments, iron oxide pigments,chromium pigments, cobalt pigments, lead pigments, copper pigments,titanium pigments, ultramarine pigments, mercury pigments, zincpigments, clay earth pigments (which include iron oxides), pigments ofbiological origin, and combinations thereof.

When used, the colorant agent is provided up to approximately 0.01percent to 5 percent by weight of the litter composition, 0.1 percent to3 percent by weight of the litter composition, 0.5 percent to 2 percentby weight of the litter composition, or about 1 percent by weight of thelitter composition.

In yet another embodiment, the litter composition further includes anodor control agent. The odor control agent includes an anti-bacterialagent, an odor control enzyme, an odor control boron compound, orcombinations thereof. One class of anti-bacterial or odor control agentsis transition metal ions and their soluble salts. Particular transitionmetals include silver, copper, zinc, ferric and aluminum salts. Moreparticularly, the transition metal includes zinc. Examples of the odorcontrol enzymes include ureases and proteases, such as pepsin, tripsin,ficin, bromelin, papain, rennin, and mixtures thereof. Examples of theodor control boron compounds include borax pentahydrate, boraxdecahydrate and boric acid. Polyborate, tetraboric acid, sodiummetaborate and other forms of boron are also appropriate alternativematerials.

Other odor control agents include sulfuric acid, phosphoric acid,hydroxamic acid, thiourea, iodophores, 3-isothiazolones, salts of phyticacid, plant extracts, pine oil, naturally occurring acids andantimicrobials, such as quaternary ammonium compounds, organic sulfurcompounds, halogenated phenols, hexachlorophene,2,4,4′-trichloro-2′-hydroxydiphenyl ether, trichiorocarbanalide,2,4-dichloro-meta-xylenol, 3,4,5-tribromosalicylanalide,3,5,3′,4′-tetrachlorosalicylanalide, and mixtures thereof. Additionalodor control (or odor-absorbing) agents include carbonates,bicarbonates, cyclodextrins, zeolites, activated carbon, kieselguhr,chelating agents, chitin and pH buffered materials, such as carboxylicacids and the like.

In yet another embodiment, the litter composition further includes oneor more fragrances to provide a freshness. The fragrance can be free orencapsulated to prevent premature fragrance loss to the atmosphere, aswell as to avoid a strong fragrance odor which can be uncomforting tothe animals. The encapsulation can be in the form of molecularencapsulation, such as the inclusion complex with cyclodextrin,coacevate microencapsulation wherein the fragrance droplet is enclosedin a solid wall material, or “cellular matrix” encapsulation whereinsolid particles containing perfume droplets stably held in the cells.Fragrances can also be more crudely embedded in a matrix, such as astarch or sugar matrix. The encapsulated fragrance can be releasedeither by moisture activation and/or a pressure activation mechanism.Moisture-activated microcapsules release fragrance upon being wetted,e.g., by the animal urine. Pressure-activated microcapsules releasefragrance when the shell wall is broken by, e.g., the scratching orstepping of the animals on the litter. Some microcapsules can beactivated both by moisture and pressure.

The fragrances can contain pro-fragrances. A pro-fragrance is a normallynonvolatile molecule which consists of a volatile fragrance ingredientcovalently bonded to another moiety by a labile covalent bond. In use,the pro-fragrance is decomposed to release the volatile fragranceingredient. Examples of pro-fragrances include complexes of bisulfite,with fragrance ingredients having an aldehyde or ketone functionalgroups, and esters of phosphoric acids, and sulfuric acids withfragrance ingredients having a hydroxyl group.

When used, the fragrance agent is provided at 0.1 percent to 3 percentby weight, particularly 0.05 percent to 2 percent by weight, and moreparticularly 0.1 to 1.0 percent by weight, of the litter composition.

In yet another embodiment, the litter composition further includes atleast one binding agent to induce or facilitate agglomeration. Examplesof the binding agent include (i) natural polymers and syntheticderivatives thereof, including, but not limited to, lignins, gums,starches and polysaccharides, such as lignin sulfonate,carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose,ethylhydroxyethyl cellulose, methylhydroxypropylcellulose, guar gum,alginates, starch, xanthan gum, gum acacia, and gum Arabic, (ii)synthetic polymers, including, but not limited to, polyvinylpyrrolidone,polyethylene glycol, polyethyleneoxide, acrylate polymers andcopolymers, acrylic emulsions, polyvinyl alcohol, polyvinyl acetate,polyvinyl pyrrolidine, polyacrylic acid, latexes (e.g., neoprene latex),superabsorbent polymers (e.g., cross-linked polyacrylates), flocculatingagents (e.g., polycarboxylates), and fluorinated polymers (e.g.,polytetrafluoroethylene), and (iii) inorganic agglomerating agents,including, but not limited to, soluble silicates and phosphates,including pyrophosphates and aluminates.

Particularly, the binding agent includes a polysaccharide gum, and moreparticularly a galactomannan gum. As is well known in the art, agalactomannan gum is a carbohydrate polymer containing D-galactose andD-mannose units, or other derivatives of such a polymer. Galactomannangums include guar gum, which is the pulverized endosperm of the seed ofeither of two leguminous plants (Cyamposis tetragonalobus andpsoraloids), locust bean gum, which is found in the endosperm of theseeds of the carob tree (Ceratonia siliqua), and carob gum.

One particular example of the binding agent is guar gum, which iscommercially available in a wide variety of forms, including food gradeand technical grade and many variations as to grind. When used withoutother tacking or clumping agents, guar gum is not satisfactory as aclumping agent, since the clumps formed by guar gum do not maintainintegrity sufficiently for easy removal from a litter box. Clumps thatbreak apart during removal are highly undesirable, and may defeat thepurpose of using a clumping agent in the litter material entirely. Inaddition, when only guar gum is used as a clumping agent the percentageof guar gum by weight as a proportion of the total product must be veryhigh in order to be effective, around 10-15% at a minimum. An advantageof guar gum, however, is that it generally does not form a barrier tomoisture, swells well upon moisture contact, and therefore effectivelyincreases liquid absorbency of the resultant litter product.

When the bentonite and guar gum are both included in the animal litter,according to one or more embodiments of the present invention, theresultant animal litter can optimizes the best properties of bothagents. As compared to guar gum, bentonite is less organic, less liquidabsorbent, but also less expensive. By combining the bentonite and theguar gum together in the animal litter, guar gum's cost deficiency canbe buffered by the inclusion of bentonite; and at the meantime,bentonite's inorganic properties can be minimized by the inclusion ofguar gum such that the resultant litter is more organic in nature andhence more environmentally friendly. In one variation, the bentonite canbe provided in an amount of 20 to 40 percent, 25 to 35 percent, orparticularly 38 to 32 percent, by weight of the total weight of theanimal litter. In another variation, the guar gum can be provided in anamount of 5 to 15 percent, 7 to 12 percent, or 9 to 11 percent, byweight of the total weight of the animal litter.

When used, the binding agent is provided at 0.01 percent to 40 percentby weight, particularly 1 percent to 30 percent by weight, and moreparticularly 5 percent to 20 percent by weight, of the littercomposition.

In yet another embodiment, the litter composition further includes asurfactant. The surfactant can be used to increase the rate of moistureabsorption. Quick absorption reduces the likelihood that the littermaterial will stick to the sides or bottom of the litter pan, and alsomakes clumps easier to remove since they will be found more near thelitter surface. Quick absorption also improves the odor controlexhibited by the product, since urine is quickly absorbed into thelitter and odor is thereby trapped within. Several different surfactantsmay be used in alternative embodiments of the invention. Thesesurfactants include T-Det N9 or T-Det NP9 from Harcros Chemicals;Standapol WAQ-LC from the Cognis Corporation; and Wickit 1362 byHercules Corporation. The absorption rates of each of these surfactantsare quite close to one another, and any may be used with the presentinvention with success. Alternative embodiments may comprise acombination of two or more surfactant formulations based on availabilityand cost considerations. In the preferred embodiment, the percentage ofsurfactant in the product by total product weight is in the range of1-5%. This range is sufficient to ensure sufficient absorption qualitiesof the product, including sufficient absorption to allow immediateflushing of the product upon deposit in a toilet. A higher rate ofsurfactant usage will result in quicker absorption in the product.

According to another aspect of the present invention, a process forproducing an animal litter is provided. In one embodiment, and asdepicted in FIG. 1, at steps 12 and 14, raw paper material and raw woodmaterial are respectively milled to form milled paper material andmilled wood material that are finer in dimensions relative to the rawmaterials. In one variation, the raw paper material and the raw woodmaterial can be optionally milled together. At step 16, the milledmaterials are combined and mixed to form a fiber mixture. At step 18,the fiber mixture is ground to a uniform fiber consistency. The grindingaction results in an additional and simultaneous mixing of the milledmaterials, such that a uniform mixture may result. Notably, bentonite inpowder or pellets can be added to the fiber mixture prior to thegrinding at step 18. It is feasible, and depending upon particularapplications at hand, the bentonite can be added at later steps such asat steps 18, 20. The other additives, including colorant agent, odorcontrol agent, and fixing agent can be added to the fiber mixture atstep 28, step 18, and or step 20, preferably at step 14 to ensure auniform mixing.

At step 20, the ground mixture from step 18 is pelletized, optionallyvia an agglomeration process. Due to the thorough mixing at steps 16 and18, the resultant pellets can have a uniform distribution of eachmaterial throughout their volume. At steps 22 and 24, the pellets aregranulated and optionally flaked such that an end litter product isprovided with a finer consistency and a softer texture small animalsgenerally prefer. When the granules are further divided or granulatedinto flakes, the resultant litter product can be provided with increasedsurface area, increased volume-to-weight ratio, decreased bulk density,and hence reduced cost to the consumers.

The granulation process at step 22 and the flaking process at step 24,alone or in combination, help to reduce particle density of the finallitter composition, as the previous mixing, grinding and pelletizingprocesses at steps 16, 18, 20 may have caused material condensing andhence material hardening.

Having generally described several embodiments of this invention, afurther understanding can be obtained by reference to certain specificexamples which are provided herein for purposes of illustration only andare not intended to be limiting unless otherwise specified.

EXAMPLE Example 1

A sample litter composition, according to one embodiment of the presentinvention, contains the following ingredients as tabulated in Table 1.For this sample, the surfactant used is Conwet 100 and the fragranceused in Baby Powder EOC 110V16. The cellulose fiber includes fibers fromnewspapers and wood pieces.

TABLE 1 sample ingredients of a clumping animal litter Ingredients DryWeight Percent Cellulose Fiber 51.64% Bentonite Clay 30.00% Gaur Gum10.00% Sodium Bicarbonate 5.00% Kaolen Clay 2.50% Surfactant 0.66%Fragrance 0.20%

Example 2

The sample litter having ingredients tabulated in Table 1 is formedaccording to the following steps. The cellulose fibers includingnewspapers and wood pieces are hammer-milled through a screen to aconsistent particle size. Bentonite, Guar gum, Kaolen clay, sodiumbicarbonate are mixed with the cellulose fiber and run through a finishhammermill which further grinds the ingredients together to form acombined fiber mixture. The fiber mixture is then extruded through apellet-forming dye. The resultant pellets are dried and then conveyed toa granulator where they can be flaked to form litter flakes.

Example 3

A small litter is shown to have the following specifications, utilizing50 grams of finished product, as measured by a Rotap Sieve Shaker, ASTME-11 Specification #4, #8, #16, #25, #50 and Pan:

25.72% greater than 4.75 mm (range: 23% to 26%) 55.90% 4.75 mm-2.36 mm(range: 53% to 56%) 11.68% 2.36 mm-1.18 mm (range: 9% to 12%) 2.33% 1.18mm-0.71 mm (range: 1% to 3.5%) 1.27% 0.71 mm-0.30 mm (range: 0.5% to 2%)0.10% less than 0.3 mm (range: 0% to 0.5%)

This animal litter may be granulated into a larger granule for largeranimals. The subject invention is also directed to the use of the animallitter to receive urine and/or feces from animals. The animal litter maybe packaged in bulk for laboratory use in automatic bedding dispensers.In the preferred use, the animal litter of the subject invention isusually added to a box or tray, which may be part of the packagingthereof, i.e. prepackaged trays containing a recommended amount oflitter. The prepackaged trays may be sold individually or packaged instacks of several trays. The trays may be of aluminum, paper, plastic,fiberboard, etc., and may come with a releasable adhesively bandedcover. The cover may be removed from all edges or from all except a lastedge of the tray, and placed beneath the tray. When the litter is to bereplaced, the adhesive cover may be replaced and resealed, facilitatingtransport and disposal.

While an embodiment of the invention has been illustrated and described,it is not intended that the embodiment illustrates and describes allpossible forms of the invention. Rather, the words used in thespecification are words of description rather than limitation, and it isunderstood that various changes may be made without departing from thespirit and scope of the invention.

1-22. (canceled)
 23. A method for manufacturing animal litter,comprising: providing a milled paper material; combining the milledpaper material with a bentonite to form a mixture; pelletizing themixture to form litter pellets; and granulating the litter pellets toform litter granules, flakes, or both, wherein bentonite is present inan amount of from 20 to 40 percent by weight of the animal litter. 24.The method of claim 23 further comprising, prior to the step ofpelletizing, adding a milled wood material to the milled paper materialand the bentonite to form the mixture.
 25. The method of claim 23further comprising adding a surfactant prior to the step of granulating,the surfactant being present in an amount of from 1 to 5 weight percentbased on the weight of the animal litter.
 26. The method of claim 24further comprising adding a surfactant prior to the step of granulating,the surfactant being present in an amount of from 1 to 5 weight percentbased on the weight of the animal litter.
 27. The method of claim 23further comprising adding to the mixture an additive selected from thegroup consisting of an odor control agent, a colorant agent, a fixingagent, and combinations thereof.
 28. The method of claim 23 furthercomprising adding from 7 to 12 weight percent of a polysaccharide gumbased on the weight of the animal litter.
 29. The method of claim 24further comprising adding from 7 to 12 weight percent of apolysaccharide gum based on the weight of the animal litter.
 30. Themethod of claim 25 further comprising adding from 7 to 12 weight percentof a polysaccharide gum based on the weight of the animal litter. 31.The method of claim 26 further comprising adding from 7 to 12 weightpercent of a polysaccharide gum based on the weight of the animallitter.
 32. The method of claim 23 further comprising grinding themixture prior to the step of pelletizing.
 33. The method of claim 24further comprising grinding the mixture prior to the step ofpelletizing.
 34. The method of claim 25 further comprising grinding themixture prior to the step of pelletizing.
 35. The method of claim 26further comprising grinding the mixture prior to the step ofpelletizing.
 36. The method of claim 28 further comprising grinding themixture prior to the step of pelletizing.
 37. The method of claim 29further comprising grinding the mixture prior to the step ofpelletizing.
 38. The method of claim 23 further comprising, after thestep of pelletizing, drying the litter pellets.
 39. The method of claim23 further comprising passing the litter granules through a ¼ inch meshsieve.
 40. The method of claim 23 further comprising passing the litterflakes through a ⅜ inch mesh sieve.
 41. The method of claim 24, whereinthe milled wood material, milled paper material, bentonite, optionallyfrom 1 to 5 weight percent of surfactant, and optionally apolysaccharide gum are milled together prior to pelletizing, such thatat least a portion of bentonite is compounded into and impregnatedwithin fibers of the wood and paper materials.